Don't know why this happened, but on a job the other night I called up a couple of song registrations where only the style did not change from the previous song. All the other registrations changed, but not the style or tempo.

It only affected 2 songs regs I tried to play. The next day I went went into all the function menus trying to find the problem. Nothing.

So, I deleted the song registrations in question, rebuilt them...and no problem. Why it happened in the first place, I have no idea. But, if it happens to you, and you have no better solution, just delete and rebuild.
Eddie